MAPT and Alzheimer disease: Thus, the four tandem repeats of the MBD could play distinct roles in the formation of orderly β‐sheets of tau, as suggested by the different compositions of tau aggregation cores in CBD, PiD, and chronic traumatic encephalopathy.[5, 33] Negatively stained TEM showed that tau‐AC fibrils had a different morphology than that of heparin‐induced tau fibrils, with significantly thicker and shorter filament bundles, which were more likely to become a protofilamental seed and more physiologically related to human AD tau filaments.